Ceramic reed relay



J n 1 196 E. R. MYATT, JR. ETAL 3, 83, 56

CERAMIC REED RELAY Flled Aug 1. 1966 2 Sheets-Sheet 1 F/ G. 2c.

Filed Aug 1, 1966 2 Sheets-Sheet 2 H045 F/G.4IA

F/GSC v 62 5 F/GSA.

E. R. MYATT. JR, ETAL 3,388,356

United States Patent Oflice 3,388,356 Patented June 11, 1968 3,388,356 CERAMIC REED RELAY Edward Ronald Myatt, Jr., Redbourn, and Ernest Frederick Lovelaud, London, England, assignors to International Standard Electric Corporation, New York, N.Y., a corporation of Delaware Filed Aug. 1, 1966, Ser. No. 569,411 Claims priority, application Great Britain, July 30, 1965, 32,741/ 65 8 Claims. (Cl. 335-151) The invention relates to electromagnetic relays having their contact making members hermetically sealed inside an enclosure and especially to the kind employing a flat armature.

According to the invention there is provided a sealed contact assembly for a relay which includes, within a hermetically sealed enclosure, a flat plate of ferromagnetic material which has one or more slots which divide it into an inwardly projecting movable portion which forms the armature of the relay and a fixed remainder portion which provides low reluctance paths in a magnetic circuit for operating the relay, fixed contact sealed through one wall of the enclosure so as to cooperate with a contact portion of the armature, and electrical connections to the plate and hence to the armature, and to the fixed contact.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a sectional side elevation of a contact assemy;

FIGS. 2A to 2C show different shapes of armature formed in a circular plate according to the invention;

FIGS. 3A, 3B and 3C are respectively a plan view of a rectangular plate and armature; a sectional side elevation of a contact assembly incorporating the armature; and a plan view of a modified plate;

FIGS. 4A and 4B show respectively a front elevation and side elevation of a plate and armature, and an associated fixed contact;

FIGS. 5A to SC show respectively a plan view, side ele vation and end elevation of a modified armature and associated fixed contact.

Referring to FIG. 1, the contact assembly has a diaphragm 1 of ferromagnetic material with an armature 2 formed from and integral with the diaphragm. The armature 2 has a portion at its unconnected end acting as a movable contact member. The diaphragm is sandwiched between two caps 3 and 4 of electrically insulating material. A ferromagnetic rod 5 has one end 6 extending through the end cap 4 to provide a fixed contact and magnetic pole piece. The contacts are hermetically sealed inside the enclosure formed by the internal recesses of the end caps 3 and 4. For operating the contacts an energizing coil (not shown) can be Wound round the rod 5, with electrical connection made to the contacts via the rod 5 and upstanding extension of the diaphragm 1. The contact assembly in the specific form illustrated is only for the purpose of making clear the details of its basic construction. It can be altered in various respects as will be made clear later in the description. Preferably but not necessarily the end caps 3 and 4 are made of a ceramic material as also in the embodiment to be described with reference to FIGS. 3 and 4.

Where it is important that the contact assembly should be as small as possible it is difiicult to give an armature a sufiiciently high degree of flexibility not to adversely affect the operating characteristics of the assembly. Since the armature must be contained within the plate, the size of the latter has a marked bearing on the problem.

FIGS. 2A, 2B and 20 each show a circular plate or disc of ferromagnetic material with one or more slots which divide it into an inwardly projecting movable portion which forms an armature 1 and a fixed remainder portion. The remainder portion can be considered as an annular diaphragm 2 to which the armature is attached, together with portions 10 (FIG. 2A), 11 (-FIG. 2B) and 12 (FIG. 2C) which fill in the spaces between the armature 1 and the diaphragm 2. The portions 10, 11 and 12 provide paths for the passage of flux between the armature 1 and the diaphragm 2, and the whole remainder portion provides low reluctance paths in a magnetic circuit for operating the relay.

' In FIG. 2A, the armature is formed into a closed loop with its ends 7 and 8 attached to the diaphragm at ad jacent points thereof. The armature 1 has an extension 9 whose unconnected end extends to the centre of the annulus and forms the contact portion of the armature. However, if the contacts are to be offset from the centre of the device then the member 9 may be omitted. In FIG. 2B the armature is shaped in the form of a spiral. The armatures of both FIGS. 2A and 2B are of a length which if opened out is greater than the internal diameter of the diaphragm. In FIG. 2C the armature is shaped in the form of an inwardly projecting tongue.

Although the above mentioned features are described for a circular plate, they can in slightly modified form be used for other shapes of plate.

FIGS. 3A and 3B show a contact assembly having a rectangular plate 23 of ferromagnetic material hermetically sealed between two caps 24 and 25. The caps form an enclosure for an armature 26 and a fixed contact 27 on the end of a ferromagnetic rod 28 hermetically sealed into the cap 25. In this arrangement the armature 26 is parallel to the longer sides of the plate and is as long as as is conveniently possible. Thus the length of the armature is about equal to the longer dimension of the plate. Alternatively the armature could be arranged diagonally across the plate as illustrated in FIG. 3C. The armature is preferably made to extend as near as conveniently possible the distance between the two diagonally opposite corners of the plate.

With the plates illustrated in FIGS. 3A and 3C the gap between the armature and surrounding border of the plate is made narrow as possible. Then, as illustrated in FIGS. 4A and 4B, an effective leakage path exists, for the flux generated on energization of a coil 36, between the end 34 of the armature 26 and the portion 35 of the plate bordering the armature.

To reduce the likelihood of faulty operation of the contact assembly due to the contacts making poor electrical contact with each other, the armatures of the previously described diaphragms and their respective fixed contacts may be modified as illustrated in FIGS. 5A to 50 providing a cylindrical end 60 to the fixed contact and a slot 61 in the free end of the armature. The end of the fixed contact has the axis of its cylindrical end across the width of the armature. When the contacts close the two portions 62 and 63 of the armature on either side of the slot 61 are attracted independently to the fixed contact. If, therefore, one portion of the armature makes poor contact there is a good possibility that a low resistance make between its other portion and the fixed contact will exist.

It is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not to be considered as a limitation on its scope.

What is claimed is:

1. A contact assembly for a relay within a hermetically sealed enclosure comprising, a fiat plate of ferromagnetic material having at least one slot dividing it into an inwardly projecting movable portion which forms the armature of the relay and a fixed remainder portion which provides low reluctance paths in a magnetic circuit for operating the relay, a fixed contact sealed through one wall of the enclosure to cooperate with a contact portion of the armature, and electrical connections to the plate and hence to the armature, and to the fixed contact.

2. A sealed contact assembly for a light current electromagnetic relay comprising a flat plate of ferromagnetic material which has one or more slots which divide it into an inwardly projecting movable portion which forms the armature of the relay and a remainder portion which provides low reluctance paths in a magnetic circuit for operating the relay, a pair of caps of electrically insulating material sealed around the plate to form therewith a hermetically sealed enclosure between the caps, the interior surface of at least one of the caps being spaced from the armature to allow for movement of the armature, and a rod of ferromagnetic material hermetically sealed through the last mentioned cap to provide a fixed contact member and magnetic pole piece co-operat-ing with the movable contact member.

3. An assembly as claimed in claim 1 in which the flat plate is a circular disc.

4. An assembly as claimed in claim 3, in which the armature is integral with and projects inwardly from an annular portion of the plate formed by the slot or slots,

and in which the armature is of a length at least equal to the internal distance across the annular portion.

5. An assembly as claimed in claim 4, in which the armature is a flat spiral.

6. An assembly as claimed in claim 4, in which the armature is a closed loop whose ends are attached to the annular portion adjacent to each other.

7. An assembly as claimed in claim 6, in which the armature loop carries a tongue-like member whose unconnected end forms the contact of the armature.

8. An assembly as claimed in claim 2, in which the armature is provided with a slit parallel to the sides of the armature and extending from its unconnected end, and wherein the fixed contact associated with said armature has a cylindrical end thereto whose axis is arranged across the Width of said armature.

References Cited FOREIGN PATENTS 2/1966 Great Britain. 4/ 1966 Great Britain. 

1. A CONTACT ASSEMBLY FOR A RELAY WITHIN A HERMETICALLY SEALED ENCLOSURE COMPRISING, A FLAT PLATE OF FERROMAGNETIC MATERIAL HAVING AT LEAST ONE SLOT DIVIDING IT INTO AN INWARDLY PROJECTING MOVABLE PORTION WHICH FORMS THE ARMATURE OF THE RELAY AND A FIXED REMAINDER PORTION WHICH PROVIDES LOW RELUCTANCE PATHS IN A MAGNETIC CIRCUIT FOR OPERATING THE RELAY, A FIXED CONTACT SEALED THROUGH ONE WALL OF THE ENCLOSURE TO COOPERATE WITH A CONTACT PORTION OF THE ARMATURE, AND ELECTRICAL CONNECTIONS TO THE PLATE AND HENCE TO THE ARMATURE, AND TO THE FIXED CONTACT. 